Cerebral venous sinus thrombosis is an uncommon condition with a variable clinical presentation, often resulting in a delayed diagnosis. The most common risk factors are pregnancy and puerperium, oral contraceptive use, head injury, dehydration, blood dyscrasias, malignancies, and systemic diseases. We present a nineteen-year-old female in whom a superior sagittal sinus thrombosis was caused by dehydration during diabetic ketoacidosis and led to the diagnosis of new-onset type 1 diabetes mellitus. To our knowledge this is the first published report of a cerebral venous sinus thrombosis in association with diabetic ketoacidosis in an adult.